U.S. patent number 6,067,673 [Application Number 09/118,255] was granted by the patent office on 2000-05-30 for bathroom fixture using radar detector having leaky transmission line to control fluid flow.
This patent grant is currently assigned to Kohler Company. Invention is credited to William R. Burnett, Fred Judson Heinzmann, Andrew J. Paese, David C. Shafer, Steven M. Tervo, Carter J. Thomas.
United States Patent |
6,067,673 |
Paese , et al. |
May 30, 2000 |
**Please see images for:
( Certificate of Correction ) ** |
Bathroom fixture using radar detector having leaky transmission
line to control fluid flow
Abstract
Methods and devices for controlling the flow of fluid in
fixtures, such as bathroom, restroom, or kitchen fixtures, using a
radar detector with a leaky transmission line and fixtures using
such methods and devices are provided. A bathroom fixture, in
accordance with one embodiment of the invention, includes a fluid
conduit, a radar detector for detecting one or more characteristics
of one or more objects in a sensor field based on reflected
electromagnetic signals from the one or more objects in the sensor
field, and a controller coupled to the fluid conduit for
controlling a flow of fluid in the fluid conduit in response to the
detected one or more characteristics. The radar detector in
particular includes a leaky transmission line for transmitting
electromagnetic signals to form the sensor field and receiving the
reflected electromagnetic signals. In accordance with one aspect of
the invention, the sensor field is restricted from selected areas
associated with spurious signals, such as areas of flowing water,
areas near other fixtures, etc. The use of a radar detector with a
leaky transmission line can, for example, improve the control of
fluid flow in fixtures, such as bathroom fixtures.
Inventors: |
Paese; Andrew J. (Plymouth,
WI), Tervo; Steven M. (Plymouth, WI), Thomas; Carter
J. (Cedarburg, WI), Burnett; William R. (Menlo Park,
CA), Shafer; David C. (Menlo Park, CA), Heinzmann; Fred
Judson (Los Altos, CA) |
Assignee: |
Kohler Company (Kohler,
WI)
|
Family
ID: |
26731304 |
Appl.
No.: |
09/118,255 |
Filed: |
July 17, 1998 |
Current U.S.
Class: |
4/623; 4/313 |
Current CPC
Class: |
E03C
1/057 (20130101); E03D 5/105 (20130101); G01S
7/03 (20130101); G01S 13/0209 (20130101); G01S
13/18 (20130101); G01S 13/22 (20130101); G01S
13/88 (20130101); G01S 13/04 (20130101); G01S
13/56 (20130101) |
Current International
Class: |
E03D
5/00 (20060101); E03D 5/10 (20060101); E03C
1/05 (20060101); G01S 13/00 (20060101); G01S
13/02 (20060101); G01S 13/22 (20060101); G01S
13/18 (20060101); G01S 13/88 (20060101); G01S
7/03 (20060101); E03C 001/05 () |
Field of
Search: |
;4/623,302,304,313 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 353 183 A1 |
|
Jan 1990 |
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EP |
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30 08 025 |
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Sep 1981 |
|
DE |
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39 20 581 |
|
Jan 1991 |
|
DE |
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196 08 157 A1 |
|
Jul 1997 |
|
DE |
|
WO 91/13370 |
|
Sep 1991 |
|
WO |
|
Other References
"A Probing Look At Emerging Technologies and the Strategic Markets
They Create", Futuretech, 175:1-13 (Jul. 1994). .
Stover, D., "Radar on a Chip, 101 Uses in Your Life ", Popular
Science, 6 pgs. (Mar. 1995)..
|
Primary Examiner: Recla; Henry J.
Assistant Examiner: Le; Huyen
Attorney, Agent or Firm: Merchant & Gould P.C.
Parent Case Text
The present application is related to U.S. provisional application
Ser. No. 60/053,168, filed Jul. 18, 1997, entitled "Radar Detector
Using Leaky Transmission Line" and U.S. provisional application
Ser. No. 60/052,960, filed Jul. 18, 1997, entitled "Devices
Utilizing Radar Detection of a User for Initiating Fluid Flow,"
which are both incorporated herein by reference.
Claims
What is claimed is:
1. A bathroom fixture, comprising:
a housing defining a basin and a rim structure around the
basin;
a fluid conduit;
a radar detector for detecting one or more characteristics of one
or more objects in a sensor field based on reflected
electromagnetic signals from the one or more objects in the sensor
field, the radar detector including a leaky transmission line for
transmitting electromagnetic signals to form the sensor field and
receiving the reflected electromagnetic signals, the leaky
transmission line being disposed along at least a portion of the
rim structure around the basin; and
a controller coupled to the fluid conduit for controlling a flow of
fluid in the fluid conduit in response to the detected one or more
characteristics.
2. The bathroom fixture of claim 1, wherein the leaky transmission
line is disposed in an approach path to the bathroom fixture.
3. The bathroom fixture of claim 1, wherein the sensor field is
restricted from a selected area.
4. The bathroom fixture of claim 3, wherein the selected area is an
area associated with spurious signals.
5. The bathroom fixture of claim 4, wherein the bathroom fixture is
a sink and the selected area is a space in which water flows.
6. The bathroom fixture of claim 4, wherein the selected area is an
area associated with a different fixture.
7. The bathroom fixture of claim 1, wherein the leaky transmission
line is encased by the housing.
8. The bathroom fixture of claim 1, wherein the one or more
characteristics includes a presence of an object.
9. The bathroom fixture of claim 1, wherein the one or more
characteristics includes movement of an object.
10. The bathroom fixture of claim 1, wherein the one or more
characteristics includes movement direction of an object.
11. The bathroom fixture of claim 1, wherein the one or more
characteristics includes entry and exit of an object.
12. The bathroom fixture of claim 1, wherein the one or more
objects includes a person.
13. A bathroom fixture for use in a bathroom, comprising:
a fluid conduit;
a radar detector including:
a transmitter for generating electromagnetic signals;
a receiver for receiving reflections of the electromagnetic
signals;
a leaky transmission line, coupled between the transmitter and
receiver, for transmitting the electromagnetic signals to form a
sensor field restricted from one or more areas associated with
spurious signals associated with the bathroom and receiving
reflections of the electromagnetic signals from interaction between
the electromagnetic signals and one or more objects in the sensor
field; and
a detection system, coupled to the receiver, for detecting one or
more characteristics of the one or more objects using the
reflections received by the receiver and generating an output
signal; and
a controller coupled to the fluid conduit for controlling a flow of
fluid in the fluid conduit in response to the detection system
output signal.
14. The bathroom fixture of claim 13, further including shielding
disposed about the leaky transmission line for restricting the
sensor field from the one or more areas.
15. The bathroom fixture of claim 14, wherein the bathroom fixture
is a sink and the one or more areas includes a space in which fluid
flows.
16. The bathroom fixture of claim 13, wherein the electromagnetic
signals generated by the transmitter restrict the sensor field from
the one or more areas.
17. A method of controlling fluid flow of a bathroom fixture using
a radar detector having a leaky transmission line, the bathroom
fixture comprising a housing defining a basin and a rim structure
around the basin, the method comprising:
transmitting electromagnetic signals to form a sensor field using a
leaky transmission line disposed along at least a portion of the
rim structure of the housing of the bathroom fixture;
receiving, with the leaky transmission line, reflections of the
electromagnetic signals from interaction between the
electromagnetic signals and one or more objects in the sensor
field;
detecting one or more characteristics of the one or more objects
using the reflections received by the leaky transmission line;
and
controlling fluid flow in a fluid conduit of the bathroom fixture
based on
the detected one or more characteristics.
18. The method of claim 17, further including restricting the
sensor field from one or more areas associated with spurious
signals associated with a bathroom.
Description
FIELD OF THE INVENTION
The present invention is generally directed to the use of radar
detection of an object or individual to control fluid flow. The
present invention is in particular directed to methods and devices
for controlling the flow of fluid in bathroom or restroom fixtures
using a leaky transmission line and bathroom or restroom fixtures
using such methods and devices.
BACKGROUND OF THE INVENTION
In light of concerns about public health and safety, the
development of touchless controls on bathroom and restroom fixtures
has received a large amount of attention. Germs, bacteria, disease,
and other harmful materials may be spread from one person to
another by touching the handles on toilets, urinals, sinks, and
other fixtures in public and private bathrooms.
A variety of touchless control systems have been developed. The
most common type of touchless control employs an infrared or, less
commonly, a visible light detector for sensing a user. The detector
typically provides signals that open or close an actuator, such as
a valve, attached to a water inlet conduit of the fixture to, for
example, flush a toilet or cause a stream of water to flow out of a
faucet Infrared radiation can be detected passively by sensing heat
from a user. Alternatively, infrared light can be emitted by a
device, such as a light emitting diode (LED), and reflected off a
user to an infrared detector, such as a photocell.
The use of infrared detection has several limitations. First,
infrared radiation cannot penetrate most materials because of the
short wavelength of the radiation. Thus, infrared emitters and
detectors are typically either exposed or are positioned behind a
window made of material that is transparent to infrared radiation.
In addition, infrared sensors can be inadvertently or purposefully
blocked by some material, such as paper, dust, or cloth, in front
of the emitter or detector.
Another disadvantage of infrared detection is that the reflectivity
of objects, such as clothing, may vary widely. Thus, the infrared
detector must be sensitive to a wide variation in the strength of
reflected signals. There is a risk that the detector may fail to
detect a user with clothing or other articles that absorb or only
weakly reflect infrared radiation.
These disadvantages of infrared detectors may cause faulty
responses by the fixture (e.g., flushing of a toilet at an
inappropriate time or constant flow of water in a toilet or sink)
or may result in a failure to operate until the sensor area is
cleaned or blocking objects are removed. Thus, there is a need for
a new type of detector that can overcome these deficiencies of
current detectors.
SUMMARY OF THE INVENTION
The present invention generally provides methods and devices for
controlling the flow of fluid in bathroom or restroom fixtures
(hereinafter "bathroom fixtures") using a radar detector with a
leaky transmission line and bathroom fixtures using such methods
and devices. The use of a radar detector with a leaky transmission
line can, for example, improve the control of fluid flow in
bathroom fixtures.
A bathroom fixture, in accordance with one embodiment of the
invention, includes a fluid conduit, a radar detector for detecting
one or more characteristics of one or more objects in a sensor
field based on reflected electromagnetic signals from the one or
more objects in the sensor field, and a controller coupled to the
fluid conduit for controlling a flow of fluid in the fluid conduit
in response to the detected one or more characteristics. The radar
detector in particular includes a leaky transmission line for
transmitting electromagnetic signals to form the sensor field and
receiving the reflected electromagnetic signals. In accordance with
one aspect of the invention, the sensor field is restricted from
selected areas associated with spurious signals, such as areas of
flowing water, areas near other fixtures, etc.
The above summary of the present invention is not intended to
describe each illustrated embodiment or every implementation of the
present invention. The figures and the detailed description which
follow more particularly exemplify these embodiments.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention may be more completely understood in consideration of
the following detailed description of various embodiments of the
invention in connection with the accompanying drawings, in
which:
FIG. 1 is a schematic block diagram of an exemplary fluid flow
control device according to one embodiment of the invention;
FIG. 2 is a side elevational view of an exemplary sink and faucet
with the fluid flow control device of FIG. 1;
FIG. 3 is a schematic block diagram of an exemplary radar system in
accordance with another embodiment of the invention;
FIG. 4 is a timing diagram for an exemplary embodiment of the radar
system of FIG. 3 which utilizes RF transmitter bursts;
FIG. 5 is a timing diagram for another exemplary embodiment of the
radar system of FIG. 3 which utilizes ultra-wideband (UWB)
transmission pulses;
FIG. 6 is a schematic diagram of an exemplary detection shell of an
ultra-wideband radar system using the timing diagram of FIG. 5;
FIG. 7 is a schematic diagram of an exemplary radar system with a
leaky transmission line in accordance with one embodiment of the
invention;
FIG. 8 is a top view of an exemplary sink using a leaky
transmission line in accordance with another embodiment of the
invention;
FIG. 9 is a top view of an exemplary urinal using a leaky
transmission line in accordance with another embodiment of the
invention;
FIGS. 10A-10D are schematic block diagrams illustrating various
exemplary pathways of the leaky transmission line of the radar
system of FIG. 7;
FIG. 11 is a top view of an exemplary toilet using a leaky
transmission line in accordance with another embodiment of the
invention;
FIG. 12 is an exemplary block diagram of a burst-modified pulsed
radar sensor;
FIG. 13 is a block diagram of one exemplary embodiment of a low
power radar sensor, according to the invention;
FIG. 14 is a block diagram of a second exemplary embodiment of a
low power radar sensor, according to the invention; and
FIG. 15 is an exemplary timing diagram of a four-channel low power
radar sensor, according to the invention.
While the invention is amenable to various modifications and
alternative forms, specifics thereof have been shown by way of
example in the drawings and will be described in detail. It should
be understood, however, that the intention is not to limit the
invention to the particular embodiments described. On the contrary,
the intention is to cover all modifications, equivalents, and
alternatives falling within the spirit and scope of the
invention.
DETAILED DESCRIPTION
The present invention is directed to methods and devices for
controlling fluid flow using radar. The invention is particular
suited to controlling fluid flow in bathroom fixtures, such as
toilets, sinks, urinals, bathing tubs, showers, and so forth, based
on the detection of one or more characteristics (e.g., presence,
position, motion, and/or direction of motion) of one or more
objects (e.g., an individual) in a radar sensor field. For example,
a fluid flow control device may be attached to a water inlet
conduit of a toilet or urinal, the device using radar to detect the
entry and exit of a user from a radar sensor field around the
toilet or urinal and responding by flushing the toilet or urinal to
remove waste after the user leaves. While the present invention is
not so limited, details of the present invention will be
illustrated through the discussion which follows.
One embodiment is a fluid flow control device which includes a
radar detector with a transmitter for generating electromagnetic
signals and a receiver for processing reflections of the
electromagnetic signals. Coupled between the transmitter and
receiver is a leaky transmission line which transmits the radar
signals to form a sensor field and receives reflections of the
electromagnetic signals generated by interaction between the
signals and one or more objects within the sensor field. The fluid
flow control device also includes detection circuitry coupled to
the sensor to detect a characteristic of an individual within the
sensor field. Examples of suitable characteristics include the
presence of the individual in the sensor field, movement of the
individual in the sensor field, direction of movement of the
individual in the sensor field, or a combination thereof. An
actuator, such as a valve, is typically coupled to the detection
circuitry and configured for disposition in a conduit to control
fluid flow through the conduit. The actuator opens and closes in a
predetermined sequence in response to the detection circuitry.
This radar-controlled fluid flow control device allows for
touchless control of a device, such as a toilet, urinal, sink,
shower, bidet, or other fixture or appliance. The response of the
device is typically dictated by the ordinary actions of the user.
Such touchless controls are especially desirable in bathrooms such
as public restrooms where there is a concern that harmful germs,
bacteria, or disease may be transferred to subsequent users of the
fixture. In addition, the fluid flow control devices of the
invention may also be utilized in other situations, such as in
bathrooms or kitchens of private homes, for a variety of reasons
including the maintenance of sanitary conditions and
convenience.
The invention is also directed to the use of such fluid flow
control devices with fixtures, appliances, and devices, and in
particular with fixtures used in bathrooms and restrooms including
toilets, urinals, bidets, showers, bathing tubs, such as bathtubs
and whirlpools, hand dryers, soap or lotion dispensers, sinks, and
faucets, as well as with fixtures used in kitchens, such as sinks
and faucets.
An exemplary fluid flow control device 20 is schematically
illustrated in FIG. 1. Device 20 contains a control device or
actuator, such as a valve 22, which is operated by control
circuitry 24. A radar detector 26 sends input data to control
circuitry 24 which then determines the appropriate response. Radar
detector 26 typically includes a transmitter 28, a receiver 30, and
detection circuitry 32.
Typically, as shown in FIG. 2, actuator 22 is connected to a water
inlet conduit 34 of a fixture 36, exemplified as a faucet 38 and
sink 40, respectively. Actuator 22 is configured to open and shut
to control fluid flow into and/or through the fixture. For example,
fluid flow control device 20 may be used in conjunction with a
faucet 38 and sink 40 to control the water flow through faucet 38
into sink 40. In this case, actuator 22 is typically connected
within water conduit 34 or between water conduit 34 and faucet 38.
In one embodiment, actuator 22 is opened and water flows through
faucet 38 when a user is detected. Actuator 22 is closed and water
stops flowing through faucet 38 when the user leaves. Other
configurations of actuator 22 and other positions of actuator 22
with respect to the fixture may also be used.
An example of suitable control circuitry 24 includes a solenoid
with an armature attached to actuator 22 to open or shut actuator
22 in response to signals from radar detector 26. For example, a
current may be applied through the solenoid to move the armature
and open the actuator. An opposing current or a spring, in the
absence of current, may then be used to return the actuator to its
closed position.
Control circuitry 24 may also include complex components such as a
microprocessor which provide a programmed response based on the
signals from radar detector 26. The programmed response may depend
on the type of signal received (i.e., the presence of an individual
or motion of an individual) or the sequence of received signals
(i.e., two consecutive signals corresponding to entry and exit of
an individual from a radar sensor field). To prevent false
responses, a microprocessor-based controller may employ various
software algorithms that use signal detection and statistical
techniques, for example, signal averaging, to resolve
signal-to-noise problems caused by spurious reflections and/or
background clutter.
Radar detector 26 is a useful device for detecting an individual
and/or actions of an individual in a sensor field. In general,
radar detection is accomplished by transmitting a radar signal from
a transmitter 28 and receiving reflections of the transmitted radar
signal at receiver 30, the reflections arising from the interaction
of the radar signal with an object. The strength of the reflected
signal depends, in part, on the reflectivity of the object.
A variety of radar transmitters can be used. One type of radar
transmitter continuously radiates an electromagnetic signal, often
at a single frequency. One method for obtaining information from
this signal is to measure the frequency of the reflected signal. If
the object which reflects the signal is moving, the frequency of
the reflected signal may be Doppler-shifted and provide motion and
direction information. For example, an object moving away from the
radar detector causes the frequency of the reflected signal to
decrease and an object moving towards the detector causes the
frequency of the reflected signal to increase. It will be
appreciated that there are other continuous-wave radar systems and
methods that can be used to obtain presence, position, motion, and
direction information concerning an individual in the radar sensor
field. These radar systems and methods may also be used in the
devices of the invention.
Another type of radar system useful in practicing the invention is
pulsed radar in which pulses of electromagnetic energy are emitted
by a transmitter and reflected pulses are received by a receiver.
One exemplary pulsed radar configuration is schematically
diagrammed in FIG. 3. This radar system includes a pulse generator
50 which generates pulses at a pulse repetition frequency (PRF), a
transmitter 52 which transmits the radar signal in response to the
pulses, an optional transmitter delay circuit 53 for delaying the
radar signal, a receiver 54 for receiving the reflected radar
signal, an optional receiver delay circuit 56 for gating open the
receiver after a delay, and signal processing circuitry 58 for
obtaining the desired presence, position, motion, and/or direction
information from the reflected radar signal.
In one type of pulsed radar, a burst of electromagnetic energy is
emitted at a particular RF frequency, the length of the burst
corresponding to multiple oscillations of the signal at the radar
frequency. One example of a radar system using RF frequency radar
bursts is described in detail in U.S. Pat. No. 5,521,600,
incorporated herein by reference. In this particular radar system,
the transmit and receive signals are mixed in receiver 54 before
signal processing.
An exemplary timing diagram for this particular radar system is
provided in FIG. 4 which illustrates the transmitted RF burst 60,
the receiver gating signal 62, and the mixed transmitter and
receiver signal 64. The detection threshold 66 of the circuit may
be set at a value high enough that only a mixed transmitter and
receiver signal triggers detection. This radar system has a maximum
detection range. Detectable signals arise only from objects that
are close enough to the transmitter and receiver so that at least a
portion of a transmitted burst travels to the object and is
reflected back to the receiver within the length of time of the
burst. The sensor field of this radar system covers the area within
the maximum range of the radar system. Any object within that
sensor field may be subject to detection.
Another type of pulsed radar system is ultra-wideband (UWB) radar
which includes emitting pulses having nanosecond or subnanosecond
pulse lengths. Examples of UWB radar systems can be found in U.S.
Pat. Nos. 5,361,070 and 5,519,400, incorporated herein by
reference. These UWB radar systems are also schematically
represented by FIG. 3. However, for UWB radar systems the timing of
the transmit pulse 68 and receiver gating 70, illustrated in FIG.
5, is significantly different from the above-described RF-burst
radar systems. Transmit pulses are emitted by transmitter 52 at a
pulse repetition frequency (PRF) determined typically by pulse
generator 50. In some embodiments, the pulse repetition frequency
may be modulated by a noise source so that transmit pulses are
emitted at randomly varying intervals having an average interval
length equal to the reciprocal of the pulse repetition frequency.
Receiver 54 is gated open after a delay period (D) which is the
difference between the delays provided by the receiver delay
circuit 56 and the transmitter delay circuit 53. In UWB radar
systems, the transmit pulses have a short pulse width (PW),
typically 10 nanoseconds or less. In addition, the receiver is
usually gated open after the transmitter pulse period, in contrast
to the previously described RF burst radar systems in which the
receiver is gated open during the transmitter pulse period.
In UWB systems, the delay period and length of the receiver gating
and transmitter pulses define a detection shell 72, illustrated in
FIG. 6. The detection shell defines the effective sensor field of
the UWB radar system. The distance between the radar
transmitter/receiver and the detection shell is determined by the
delay period, the longer the delay period the further out the shell
is located. The width 73 of the shell depends on the transmit pulse
width (PW) and the receiver gate width (GW). Longer pulse widths or
gate widths correspond to a shell 74 having greater width 75. Using
UWB radar systems, characteristics of an object 76 in the shell,
such as presence, position, motion, and direction of motion of an
object, can be determined.
In some embodiments, two or more gating pulses are used. The gating
pulses may alternate with each timing pulse or after a block of
timing pulses (e.g., one gating pulse is used with forty timing
pulses and then the second is used with the next forty timing
pulses). In other embodiments, a controller may switch between the
two or more gating pulses depending on circumstances, such as the
detection of a user. For example, a first gating pulse may be used
to generate a detection shell that extends a particular distance
from the fixture. When a user is detected, a second gating pulse
may be used which generates a detection shell that is closer or
further away than the first shell. Once a user leaves this second
detection shell, the fixture may be activated, for example, a
toilet may be flushed. The controller then resumes using the first
gating pulse in preparation for another user. In yet other
embodiments, more than one gating pulse is provided per transmit
pulse, thereby generating multiple detection shells.
A potentially useful property of some UWB transmitters is that the
transmitter antenna often continues to ring (i.e., continues to
transmit) after the end of the pulse. This ringing creates multiple
shells within the initial detection shell 72 thereby providing for
detection of objects between detection shell 72 and the radar
transmitter/receiver.
In either the RF-burst or UWB radar systems, delay circuits 53, 56
provide a fixed or variable delay period. A variable delay circuit
may be continuously variable or have discrete values. For example,
a continuously variable potentiometer may be used to provide a
continuously variable delay period. Alternatively, a multi-pole
switch may be used to switch between resistors having different
values to provide multiple discrete delay periods. In some
embodiments, delay circuits 53, 56 may simply be a conductor, such
as a wire or conducting line, between pulse generator 50 and either
transmitter 52 or receiver 54, the delay period corresponding to
the amount of time that a pulse takes to travel between the two
components. In other embodiments, delay circuits 53, 56 are pulse
delay generators (PDG) or pulse delay lines (PDL).
One useful configuration of transmitter 52 and receiver 54 is shown
in FIG. 7. A leaky transmission line 80 connects transmitter 52 and
receiver 54. Leaky transmission line 80 acts as an antenna for both
the transmitter and receiver, emitting and receiving
electromagnetic signals. In one embodiment, transmitter 52 and
receiver 54 are spatially separated with transmission line 80
forming a curved (FIG. 10B), straight (FIG. 10C), or irregular
(FIG. 10D) path between the transmitter and receiver. In another
embodiment, transmitter 52 and receiver 54 are proximately disposed
to each other and transmission line 80 forms a curved (FIG. 10A) or
irregular path between the transmitter and receiver. In some cases,
the curved path may have an approximately circular or ovoid
shape.
Examples of suitable leaky transmission lines include a twisted
pair, a
twin lead transmission line, a co-axial cable, a micro-strip
transmission line, a coplanar strip or wave guide transmission
line, or a single wire Gaobau line. Leaky transmission line 80 is
arranged and configured to emit and receive sufficient radiation to
generate a detectable signal at the receiver. U.S. Pat. No.
5,581,256, incorporated herein by reference, illustrates a radar
system which uses a leaky transmission line as an antenna.
Optionally, leaky transmission line 80 may contain portions that do
not emit and/or cannot receive amounts of radiation that can be
detected by the receiver. This permits selectively choosing which
regions along transmission line 80 are to be sensed. One method for
creating portions of transmission line 80 that do not emit or
receive radar signals is to shield such portions using, for
example, a metal sheath around the line.
Typically, leaky transmission line 80 generates a sensor field 82
around the transmission line for detection of objects in proximity
to the transmission line 80. Sensor field 82 for a particular radar
system depends on the type of radar used in the detector. For
example, in the RF-burst radar systems, described hereinabove,
sensor field 82 for each emitting point on the transmission line 80
is approximately spherical with a maximum sensor range defined by
the burst width. In the UWB radar systems described hereinabove,
sensor field 82 for each emitting point on the transmission line
has the form of a detection shell located a particular distance
from line 82 depending on the relative delay between the
transmission pulse and the receiver gating pulse. The detection
shell has a width that depends on the width of the transmission and
receiver gating pulses.
In any radar system, sensor field 82 is a sum of the sensor fields
generated at individual points along transmission line 80.
Typically, sensor field 82 has an approximately tubular or
cylindrical shape centered around transmission line 80.
Radar signals from sensor field 82 can be used to detect presence,
position, motion, and/or direction of motion using any of the
above-described radar methods. Because of their versatility, radar
systems can detect various characteristics of an individual in a
radar sensor field (i.e., within the radar's detection range). For
example, the presence of an individual can be detected from the
strength of the return signal. This return signal can be compared
with a background signal that has been obtained in the individual's
absence and stored by the detector.
Another type of presence detector includes a transmitter and
receiver separated by a region of space. The receiver is only gated
open for a period of time sufficient to receive a signal directly
transmitted from the transmitter. If the signal is reflected or
blocked, it either does not arrive at the receiver or it arrives
after the receiver is gated closed. This type of detector is a
"trip wire" that detects when an individual or a portion of an
individual is interposed between the transmitter and receiver.
Presence of an individual is indicated when the signal received
during the gating period is reduced.
Position of the individual in the sensor field can be determined,
for example, by sweeping through a series of increasingly longer,
or later, receiver gating pulses. The detection of a reflected
signal, optionally after subtraction of a background signal,
indicates the distance of the individual away from the radar
system. Motion of an individual can be determined by a variety of
methods including the previously described Doppler radar system. An
alternative method of motion detection is described in U.S. Pat.
Nos. 5,361,070 and 5,519,400 in which a received signal is bandpass
filtered to leave only those signals that can be ascribed to human
movement through the sensor field. Typically, the bandpass filter
is centered around 0.1-100 Hz.
U.S. Pat. No. 5,519,400 also describes a method for the
determination of the direction of motion of an individual. This
method includes the modulation of the delay period by 1/4 of the
center frequency of the transmission pulse. Quadrature information
can be obtained and used to determine the direction of motion of an
object in the sensor field (e.g., toward and away from the
detector).
Another method for detecting direction of motion is to compare
consecutive signals or signals obtained over consecutive periods of
time. For many radar systems, the reflected signal strength
increases as an individual moves closer. As the individual moves
further away, the signal typically decreases. The comparison of
successive signals can then be used to determine the general
direction of motion, either toward or away from the radar detector.
The control circuitry may not activate the actuator prior to
confirming the direction of the user over a period of time (e.g.
3-10 seconds) to ensure that the user is moving toward or away from
the fixture.
One or more characteristics of an individual in the sensor field,
such as presence, position, motion, or direction of motion, may be
simultaneously or sequentially detected by one or more sensors.
This information may be coupled into the control circuitry which
determines an appropriate action. A microprocessor may be used to
control the actuator based on these multiple pieces of information
It will be appreciated that other methods may also be used to
determine the presence, position, motion, and direction of motion
of an individual in a radar sensor field.
Fluid flow control devices utilizing radar detectors are useful in
a wide variety of applications. Of particular interest is the use
of such devices in bathroom fixtures, such as urinals, toilets,
bidets, hand dryers, soap dispensers and faucets. Radar-control of
fluid flow can facilitate the operation of these fixtures without
active participation by the user. Instead the fixture operates in
response to ordinary actions of the user including approaching the
fixture, leaving the fixture, and placing a body part, such as a
hand, in proximity to the fixture.
One advantage of using a leaky transmission line radar system is
that the shape of the sensor field can be configured as desired by
adjusting the path of the leaky transmission line. The sensor field
can then be oriented around a desired detection region or oriented
to avoid a region from which unwanted radar reflections may
arise.
A particularly useful application which illustrates the versatility
of the transmission line sensor field is a radar-controlled faucet
38 for use with a sink 40, as shown in FIG. 8. A leaky transmission
line 80, connecting a radar transmitter 52 and receiver 54, can be
wrapped around a portion of the outer rim of sink 40 to generate a
sensor field 82 that includes the interior of sink 40. A fluid flow
control device utilizing this type of radar system can then be used
to detect when a user places a body part, such as the user's hands,
into the sink. The fluid flow control device controls the flow of
water based on the user's actions. For example, if the user places
a portion of his body, such as his hands, or an inert object, like
a comb or toothbrush, into sink 40, the fluid flow control device
responds by allowing water to flow out of faucet 38. When the user
removes his hands, the fluid flow control device halts the flow of
water out of faucet 38.
The response of the fluid flow control device is dictated by radar
signals received as the user intersects and moves within sensor
field 82. Transmitter 52 may transmit continuous radar energy or
may provide RF bursts or UWB pulses. Receiver 54 may include
circuitry to detect signal fluctuations due to presence, position,
motion, or direction of motion of the user within sensor field
82.
The shape of sensor field 82 can be used to overcome a significant
difficulty in the design of radar sensors for faucets; namely,
radar reflections from the stream of water flowing out of the
faucet. If sensor field 82 includes the region of space through
which the stream of water flows, a radar detector may not recognize
that a user's hands have left the sink due to the high radar
reflectivity of water. In this case, the radar signal is likely to
be only slightly diminished, if at all, once the user leaves the
sensor field 82.
The use of a leaky transmission line 80 as an antenna may overcome
this difficulty because the sensor field 82 may be restricted to a
region which includes portions of the sink in which a user's body
parts are likely to be found, but does not include the stream of
water. The restriction of sensor field 82 can be accomplished by,
for example, limiting the amount of power that is transmitted along
the transmission line 80 or, if pulsed radar techniques are used,
by gating the receiver for a particular range, which excludes the
stream of water.
FIG. 9 illustrates the use of a radar detector with a transmitter
52, receiver 54, and leaky transmission line 80 in a urinal 84. In
one embodiment, illustrated in FIG. 9, leaky transmission line 80
is provided around an approach path or a portion of urinal 84 from
which a user is expected to approach. In another embodiment (not
shown), line 80 is provided only near a front portion of urinal 84.
Sensor field 82 of line 80 should extend about 6-18 inches beyond
urinal 84 to detect users. Transmitter 52 and receiver 54 may be
positioned, for example, on the exterior of urinal 84, on plumbing
or water inlet conduits attached to urinal 84, or on/in a wall to
which urinal 84 is attached. In one embodiment, line 80 and,
optionally, transmitter 52 and receiver 54 are positioned within
the vitreous china or porcelain of the urinal 84. In another
embodiment, line 80 is disposed around the outer surface of urinal
84 and, preferably, encased by an insulating material.
FIG. 11 illustrates the use of a radar detector with a transmitter
52, receiver 54, and leaky transmission line 80 in a toilet 86. In
one embodiment, line 80 is disposed around the portion of bowl 88
from which a user is expected to approach toilet 86. Sensor field
of line 80 should extend 12-36 inches, and preferably 18-24 inches,
beyond toilet 86 to detect users. Transmitter 52 and receiver 54
may be positioned, for example, on the exterior of toilet 86, on
plumbing or water inlet conduits attached to toilet 86, or on/in a
wall to which toilet 86 is attached. In one embodiment, line 80
and, optionally, transmitter 52 and receiver 54 are positioned
within the vitreous china or porcelain of the toilet 86. In another
embodiment, line 80 is disposed around the outer surface of toilet
86 and, preferably, encased by an insulating material.
The use of a leaky transmission line provides for a radar detector
with a sensor field that can be shaped to fit the environment. This
may permit the use of radar detection in situations where spurious
signals may be generated For example, water flowing in a sink may
cause reflections that confuse a radar detector. In addition,
several fixtures near each other, such as in public restrooms, may
interfere with each other. Use of a leaky transmission line as an
antenna may provide for more directed radar emissions that can be
constrained within a particular space, if the receiver is gated or
if the radar signals beyond a certain distance produce reflections
that have less than a threshold strength.
A radar sensor for use with a fluid flow device, or with any other
device, can operate using either ac or dc power. Although in many
cases the radar sensor may operate using available ac power from an
outlet, it may be convenient to use battery power instead. For
example, radar sensors operating in bathroom fixtures may not be
conveniently or aesthetically connectable to an outlet. In such
cases, a battery-powered radar sensor may be desirable. However, it
is also desirable that the lifetime of the batteries in the sensor
be measured on the order of months or years. Thus, the development
of low power radar sensors is desirable.
Often pulsed sensors can use less power than those that operate
continuously. Moreover, generally, the fewer pulses emitted per
unit time, the less power needed for operation of the sensor.
However, sensitivity often decreases with a decrease in pulse rate.
In addition, it has been found that decreasing the pulse rate can
also raise the impedance of a sampler in the receiver. This can
place limits on the bandwidth of the sensor because even small
amounts of stray capacitance can cause the frequency response of
the receiver to roll off at very low frequencies. In addition, high
output impedance may place stringent requirements on subsequent
amplifier stages and provide a very susceptible point in the
circuit for noise coupling.
A new low power radar sensor operates by providing radar pulses
that are nonuniformly spaced in time. In operation, a burst 102 of
pulses 104 is initiated in the transmitter, as shown in FIG. 12.
Between each burst is a period 106 of rest time in which the
transmitter is not transmitting RF energy. For example, a 1 to 100
microsecond burst of RF pulses may be made every 0.1 to 5
milliseconds. The RF pulses may be provided at, for example, a 0.5
to 20 MHz rate within the burst with an RF frequency ranging from,
for example, 1 to 100 GHz. In this way, there is a relatively high
pulse rate during the burst period, but with overall low power
because the bursts only occur for 5% or less of the period between
bursts. Although, the sensitivity of this radar sensor may be
approximately the same as a radar sensor with the same number of
pulses uniformly spaced in time, the impedance of the sampler
during the burst period can be much less. In some embodiments,
however, the burst period may be 10%, 25%, 50%, or more of the time
between bursts.
One exemplary low power radar sensor 200 which uses a leak
transmission line is illustrated in FIG. 13. The radar sensor 200
includes a burst initiator 202 that triggers the beginning of the
burst and may, optionally, trigger the end of the burst. A burst
rate is defined as the rate at which bursts are provided. The burst
width is the length of time of the burst. The time between bursts
is the rest period. For many applications, the burst rate can range
from, for example, 200 Hz to 10 kHz and often from, for example,
500 Hz to 2 kHz. The burst width can range from, for example, 1 to
200 microseconds and often from, for example, 5 to 100
microseconds. However, higher or lower burst rates and longer or
shorter burst widths may be used The particular burst rate and
burst width may depend on factors, such as the application and the
desired power usage. An exemplary burst 102 is illustrated in FIG.
12.
The burst starts a pulse oscillator 204 that provides the
triggering signals for each pulse. The pulse oscillator may operate
at, for example, 0.5 to 20 MHz, and often from, for example, 2 to
10 MHz to provide, for example, 5 to 2000 pulses per burst. Higher
or lower oscillator rates and larger or smaller numbers of pulses
per burst may be used, depending on factors, such as, for example,
the application and the desired power usage.
These triggering signals are provided along an optional transmitter
delay line 206 to a pulse generator 208 that produces a pulse with
a desired pulse length The optional transmitter delay line 206 may
provide a desired delay to the transmission pulses to produce a
desired difference in delays between the transmitter and receiver
pulses. In some embodiments, the transmitter delay line 206 is used
to provide a delay of, for example, one quarter wavelength of an RF
oscillator frequency to allow for quadrature detection, as
described below.
The pulse generator provides a pulse with a desired pulse length at
each pulse from the pulse oscillator. The width of the pulse
determines, at least in part, the width of the detection shell, as
described above. The pulse width may range, for example, from 1 to
20 nanoseconds, but longer or shorter pulse widths may be used. An
example of the pulses 104 from the pulse oscillator is provided in
FIG. 12.
The pulse is then provided to an RF oscillator 210 that operates at
a particular RF frequency to generate a pulse of RF energy at the
RF frequency and having a pulse width as provided by the pulse
generator 208 at a pulse rate determined by the pulse oscillator
204 during a burst period as initiated by the burst initiator 202.
The RF frequency may range from, for example, 1 to 100 GHz, and
often from, for example, 2 to 25 GHz, however, higher or lower RF
frequencies may be used. The pulses of RF energy are provided to a
leak transmission line 212, as described above. The short duration
of the pulses typically results in the irradiation of an
ultra-wideband (UWB) signal. In addition, the leaky transmission
line 212 may ring, thereby providing multiple detection shells for
each pulse.
The pulse oscillator 204, in addition to producing pulses for the
transmitter, also provides pulses to gate the receiver. The use of
the same pulse oscillator 204 for the transmitter and receiver
portions of the radar sensor 200 facilitates timing between the
portions. Pulses from the
pulse oscillator 204 are sent to the receiver delay line 214 that
delays the pulses by a desired time period to determine, at least
in part, the distance of the detection shell from the radar sensor,
as described above. The receiver delay line 214 may be capable of
providing only one delay or a plurality of delays that can be
chosen, as appropriate, to provide different radar ranges.
After being delayed, the pulses are provided to a receiver pulse
generator 216 that generates a receiver pulse with a desired pulse
width. The width of this pulse, as well as the width of the
transmitter pulse, determine, at least in part, a width of the
detection shell, as described above. Only during the receiver pulse
is the receiver gated open, via, for example, a diode 218, to
receive radar signals. The pulse width of the receiver pulse
typically ranges from zero to one-half of the RF cycle time (e.g.,
zero to 86 picoseconds at a 5.8 GHz transmit frequency), and often,
from one-quarter to one-half of the RF cycle time (e.g., 43 to 86
picoseconds at a 5.8 GHz transmit frequency). However, longer pulse
widths may also be used. Receiver pulses 108 are only produced
during the burst 102, as illustrated in FIG. 12. The receiver
pulses 108 may or may not overlap with the transmitter pulses
104.
Receiver signals are received via the leaky transmission line 212,
but these signals are only sampled during the receiver pulses. The
sampling occurs at, for example, a sample and hold component 222.
Typically, the sample and hold component 222 includes a gate that
can be opened between bursts to isolate the remainder of the
circuit. The receiver signal is then provided to one or more
amplifier stages 224. Multiple amplifier stages may be used to
provide simultaneous outputs from multiple transmitter and receiver
delay line settings.
The signal is then provided to an optional A/D converter 226 which
then sends a corresponding digital signal to a processor 228, for
example, a microprocessor that evaluates the signal and provides a
response. The processor 228 may operate an actuator 230 according
to the converted receiver signal. For example, the processor may
direct the actuator 230 to open or close a valve 232.
Alternatively, the receiver signal may be analyzed using an analog
processor (not shown) that may then operate the actuator.
It will be understood that this low power radar sensor may be used
to operate devices other than an actuator or a valve. In addition,
components such as one or more of the amplifier stages, the A/D
converter, and the processor may be included with the radar sensor
or they may be external to the sensor.
Another exemplary low power radar sensor 300 which uses a leaky
transmission line is illustrated in FIG. 14. The radar sensor 300
includes a burst initiator 302, pulse oscillator 304, transmitter
delay line 306, pulse generator 308, RF oscillator 310, and a leaky
transmission line 312, as described above for radar sensor 200. An
I/Q select 307 is optionally provided on the transmitter delay line
306. The I/Q select 307 can change the transmission pulse delay by,
for example, one quarter of a cycle of the RF frequency of the RF
oscillator 310. This can be used for quadrature detection to enable
determination of the direction of movement of an object within the
sensor field. For example, during a first burst, the transmission
pulse delay may be a first time and during a second burst the
transmission delay may be a second time that is a combination of
the first time and one quarter of the cycle time at the RF
frequency. The radar sensor may continue to alternate; using the
corresponding signals for quadrature detection to determine
direction of movement In some embodiments, more than one burst may
be provided before alternating or the alternation may occur during
a burst.
The receiver portion of the radar sensor 300 includes a receiver
delay line 314 coupled to the pulse oscillator 304, a pulse
generator 316, and the leaky transmission line 312, similar to
those described for radar sensor 200. An optional range select 315
is provided with the receiver delay line 314 to selectively alter
the delay provided by the receiver delay line 314.
An exemplary sample and hold component coupled to the leaky
transmission line 312 and pulse generator 316 is illustrated in
this embodiment, however, other sample and hold components can be
used. The sample and hold component includes a first buffer 340
(e.g., an operational amplifier with gain of about one), a gate
342a (e.g., a transmission gate), a hold capacitor 344a connected
to ground, and a second buffer 346a.
This embodiment also illustrates the use of a two channel device
with the second channel having a gate 342b, a hold capacitor 344b
connected to ground, and a second buffer 346b. In this embodiment,
both channels use the same first buffer, but individual first
buffers could also be used. It will be understood that other
embodiments may have only one channel or they may have three or
more channels. Each channel has a channel select 348a, 348b coupled
to the gate 342a, 342b to open and close the channel. All of the
channels are typically closed between bursts and typically only one
channel is open during each burst. This isolates the subsequent
amplifiers except when a signal for a particular channel is
received.
The signal from each channel is then passed through one or more
amplifier stages 324a, 324b. The amplified signal can then be
processed by, for example, analog circuitry (not shown) or by an
A/D converter 326 and a processor 328. The processed signal can
then be used to operate, for example, an actuator 330 to open or
close a valve 332. It will be understood that the radar sensor can
also be used for other purposes than operating an actuator and a
valve.
In this radar sensor 300, the processor 328 may be a microprocessor
that also operates as the burst initiator 302, I/Q select 307,
range select 315, channel 1 select 348a, and/or channel 2 select
348b. Alternatively, one or more other microprocessors or other
components can provide one or more of these functions.
An exemplary timing diagram for a four channel radar detector with
in-phase and quadrature detection at a near and a far range is
illustrated in FIG. 15. The burst channel 400 produces bursts at
regular intervals according the burst rate. The I/Q select channel
402 alternates between in-phase (no signal in I/Q select channel)
and quadrature detection (signal in I/Q select channel). The
presence of a signal in the I/Q select channel can cause, for
example, the transmission delay line to increase the delay of the
transmission pulses by, for example, one-quarter of a wavelength of
the RF frequency.
The range channel 404 allows for in-phase and quadrature detection
at a near range (no signal in range channel) followed by in-phase
and quadrature detection at a far range (signal in range channel).
The presence of a signal in the I/Q select channel can cause, for
example, the receiver delay line to provide a longer delay.
Each of the channel selects is operated one at a time to provide an
appropriate signal through the appropriate channel. For example, as
illustrated in FIG. 15, channel one 406 corresponds to in-phase
detection at a near range, channel two 408 corresponds to
quadrature detection (when combined with the signal from channel
one) at a near range, channel three 410 corresponds to in-phase
detection at a far range, and channel four 412 corresponds to
quadrature detection (when combined with the signal from channel
three) at a far range. In this particular embodiment, channel
information is obtained at one quarter the burst rate.
The number of channels, their assignment to particular signals, the
order of detection, the number of bursts before changing channels,
and other similar aspects of the timing diagram can be altered. By
using such timing mechanisms, a variety of different signals can be
obtained and used to determine characteristics of an object, such
as presence, motion, and/or direction of motion, in the sensor
field.
One example of the use of a low power radar sensor for fluid flow
control device is with a sink and faucet. A single channel or
multi-channel (in which only one channel is actively used) device
can be used to detect the presence or movement of a user in the
radar field. A metered flow of water may be provided from the
faucet when a user is detected. Alternatively, water may be
provided until the presence or movement of the user is no longer
detected. A similar sensor can also be used with a urinal, toilet,
or a variety of other devices, including bathroom, restroom and
kitchen fixtures.
Another example is a toilet. Two channels of a radar sensor are
used to determine motion and direction of motion of a user. When
the radar sensor detects a user moving away from the toilet after
having previously detected a user moving toward the toilet, then
the radar sensor can direct the toilet to flush. The radar sensor
might also include more complex instruction, such as, for example,
requiring a certain period of time that the user is detected
approaching the toilet and a period of time between the approach to
the toilet and movement away from the toilet before deciding that a
valid flush condition exists. This configuration can also be used
with faucets, urinals, and a variety of other devices, including
bathroom, restroom and kitchen fixtures.
Yet another example utilizes three channels. The radar sensor is
configured to detect motion at a far range, motion at a near range,
and direction of motion at a near range. In the example of a
toilet, the radar sensor knows to flush if the following sequence
(or alternatively a subset of this sequence) occurs: 1) motion at
the far range, 2)motion at the near range, 3) motion toward the
toilet, 4) motion away from the toilet, and 5) motion at the far
range. Again, the radar sensor may include more complicated
instructions regarding the time of or times between these events.
This configuration can also be used with faucets, urinals, and a
variety of other devices, including bathroom, restroom and kitchen
fixtures.
As noted above, the present invention is applicable to the control
of fluid flow in a number of different fixtures. Accordingly, the
present invention should not be considered limited to the
particular examples described above, but rather should be
understood to cover all aspects of the invention as fairly set out
in the attached claims. Various modifications, equivalent
processes, as well as numerous structures to which the present
invention may be applicable will be readily apparent to those of
skill in the art to which the present invention is directed upon
review of the present specification. The claims are intended to
cover such modifications and devices.
* * * * *